[Fai Mao]

In naval artillery parlance caliber is barrel length measured by the multiple of the projectile diameter. For example the USS New Jersey has 16 inch, 50 caliber cannons, meaning the barrels are 50X16 inches.

But that would make sense in this article.

[Who is John Galt?]

In naval artillery parlance caliber is barrel length measured by the multiple of the projectile diameter. For example the USS New Jersey has 16 inch, 50 caliber cannons, meaning the barrels are 50X16 inches.

Yes, I figured the small arms usage was appropriate for this article, but am also familiar with the other use you mention. It's associated in part with some trivia - if I remember correctly, one of the 15 inch, 42 caliber guns on HMS Warspite hit the Italian battleship Julius Caesar at a range of 28,500 yards, which may still stand as a record for conventional naval artillery in combat...

;>)